Enrichment characteristics of associated elements of Late Permian coal and coal ash from Pu'an and Qinglong coal mining area in Guizhou Province

ICP-MS and ICP-AES were applied to study the geochemical characteristics of trace element content of eight representative coal samples and seven coal ash samples from Late Permian coal seams C17, C19, C22 and C26 in Pu'an and Qinglong coal mining areas. The results showed that the elements such as Li, Sc, V, Cr, Co, Ge, As, Nb, Mo, W and U are enriched obviously in coal and coal ash. Compared with the concentrations of elements from coal samples, the elements from coal ash are further enriched, the content of Nb, Zr, V and U reached or exceeded the cutoff grade or the lowest industrial grade. Evidence suggests that enrichment of V, Co,Ni and Cr can be attributed to the weathered detrital materials of Emeishan basalt, at the same time, the sedimentary environment is also one of the factors that could influence the enrichment of some elements. For example, U, S and Mo are inclined to be enriched when the action of sea water became strong. Some elements like Li, Nb, Zr, Mo and U are consistently enriched and affected by the sedimentation of synsedimentary volcanic ash. Furthermore, the low temperature hydrothermal activity after coal-forming peroid made coal seams, especially the bottom coal seams(C19, C26) obviously enriched in specific elements such as As, Mo, U and W. It is concluded that the sed imentation of synsedimentary volcanic ash and the low temperature hydrothermal activity were together the main control factors effecting the enrichment of the associated elements in the Late Permian coal through comprehensive analysis.